1. Technical Field of the Invention
The present invention relates to a cab for earth-moving machines.
2. Prior Art
Earth-moving machines are composed of a frame mounted on four wheels, of at least an articulated arm fastened to the frame and bearing a work tool (such as a shovel), and a cab for housing an operator, mounted on the frame. Alternatively, the frame can be equipped with tracks instead of wheels.
Such machines further comprise a driving system an a system for actuating the arm, motorized and able to be activated by the operator.
Hereafter, reference shall be made in particular to earth-moving machines of the category known in the art with the name of xe2x80x9cskid steer loaderxe2x80x9d, whereto the subject invention is preferably destined. However, the invention is applicable in general to every kind of earth-moving machine.
The cab is composed of a structure having an opening to allow the entry and the exit of an operator into and out of the cab itself.
In the interior compartment of the cab is defined a control station for the operator, generally constituted by a seat in front of which are located the levers for controlling the equipment of the machine.
The machine is activated by the operator by means of two control levers positioned one to his/her right and the other to his/her left, and connected one to the driving system and the other to the system for actuating the articulated arm.
The driving system and the system for actuating the articulated arm are both constituted by a hydraulic servo control system connected between one of the control levers and the related activated organ. The cab is also provided with one or more control panels for controlling the operation of the machine. Such panels are typically fastened to the upper part of the cab frontally relative to the control station.
The cab is further provided with a safety bar which allows the operator to remain secured to the seat during the operation of the machine, and to avoid the risks connected to the use of the machine.
Such machines are often used on rough terrain so that there is always the risk that they may be overturned and that the operator be ejected from the cab.
The bar is pivotally fastened to the cab and can move from a safety position in which, as stated, it secures the operator on the seat, to a non operative position in which the operator is free to sit and get up from the seat.
In the prior art, substantially two types of bars exist.
A first type is represented by bars constituted by a single arm, prevalently xe2x80x9cCxe2x80x9d shaped. This arm can be fastened to the cab at one or both ends, and can rotate about a longitudinal or a transverse axis, both defined with reference to the direction of advance of the machine. The arm can be fastened to the cab in such a way as to orient, in the safety position, its concave part towards the operator, as taught in U.S. Pat. Nos. 5,050,700 and 5,971,434.
A second known type of safety bar is constituted by two arms, substantially xe2x80x9cLxe2x80x9d shaped. These arms are pivotally fastened with their shorter portion to the cab, and each can rotate about a longitudinal axis of rotation.
The two arms are mounted symmetrically relative to the seat, so that, when they are brought to the safety position, their free ends mutually engage to form in co-operation the safety bar.
In the non-operative position, the arms are located each in a substantially vertical plane, to the two sides of the seat.
Also widely used are automatic safety devices connected to the safety bars, to stop the engine when the bar is in the non operative position, in order to prevent the machine from operating without an operator sitting at the controls.
The prior art described, however, presents several drawbacks.
In the first place, the location of the control panel is such that the operator, to observe it, must orient his/her gaze upwards. This is very annoying particularly on sunny days, as the operator can be dazzled or at the very least be bothered by the reflection of the sun.
In addition to being an annoyance, this is also a source of risk because, under such circumstances, the operator is induced to be distracted and can lose control of the machine.
Additionally, the operator cannot even move to a shaded area, since this is prevented by the safety bar which blocks his/her movements.
A further drawback is represented by the working position the operator is obliged to assume because of the combined action of seat and bar.
The operator in working position is naturally induced to orient his/her gaze towards the ground in front of him/her, in the working area of the shovel or other tool.
However, when he/she has to check any parameter of the machine on the control panel, he/she has to raise his/her head and look in a direction that is not the optimal one for his/her job, with the consequent risks of losing control of the shovel.
Moreover, the continuous motion of the head to shift attention from the tool to the control panel inevitably brings the operator to an undesired level of tiredness.
The shape and disposition of the internal organs of the cabs currently used are thus lacking from the ergonomic point of view.
In this situation the technical task serving as the basis for the present invention is to obtain a cab for earth-moving machines which overcomes the aforesaid drawbacks.
Another technical task of the present invention is to obtain a cab for earth-moving machines which is particularly ergonomic.
The specified technical task and the indicated aims are substantially achieved by a cab for earth-moving machines as described in the accompanying drawings.